The motion picture projectionist (Nov 1931-Jan 1933)

December, 1931 Motion Picture Projectionist 21 Nearing the Television Goal Line By Herbert S. Futran There has been manifest on the part of the general public during the past several months a marked increase in interest toward the subject of television. While it may not perhaps be said that the man in the street has become television minded, he has, at least, become television conscious. Not a little of the interest which has been aroused has been due to the fact that it is now possible to project the televised picture on a screen approximating in dimensions those used in small motion picture theatres. In the following article, Mr. Herbert S. Futran of the Sanabria Giant Television Corporation describes the apparatus and the method by which this greatly enlarged screen image is obtained. — The Editor. AFTER years of laboratory experiment, television is evolving into a new form which will ultimately bring its acceptance as a form of entertainment as vital and as universal as the radio and, possibly, even the talking picture. Recent demonstrations have brought home to an increasing public the realization of the practical possibilities of television. With few exceptions, that very small part of the public who knew anything about television had encountered only the diminutive "peep-hole" pictures which measured but a few inches square. As long as television pictures were no larger than that, the growth of television could be but an experimental development. Wider Possibilities Demonstrated In recent months, however, many of the wider possibilities of television have been demonstrated and the public is showing a keener interest in the development of the art of visual broadcasting. One of the most revolutionary developments is the large ten-foot picture which Ulises A. Sanabria of Chicago demonstrated with great success on recent occasions at the Madison Square Garden and during a theatrical engagement of television at the Broadway Theatre in New York. Experimenters have labored, to achieve apparatus capable of transmitting an image which could be shown on an enlarged screen. It remained, however, for this young Chicagoan, who has just recently passed his twenty-fifth birthday, to pave the way with his ten-foot picture, which is the largest image ever shown to the public. The many thousands who saw the apparatus during the recent demonstrations have asked how Sanabria achieves so brilliant and so large a picture. Fig. 1. Engineers Adjusting the Equipment He uses a scanning disc employing only forty-five holes in the apparatus which was used in both the Madison Square Garden and the Broadway Theatre demonstrations, but, by virtue of remarkable developments in his technique, he is able to achieve an astounding degree of definition. Very minute details such as the bristles in a man's beard, the design in his cravat or the reflection of his spectacles are reproduced with startling fidelity. It is obviously impossible to broadcast a picture as a unity. It is necessary to "break up" every picture into smaller elements which can be translated into electrical impulses. This process of decomposition is achieved through scanning. The "Flying Spot" A single beam of light is projected through a disc perforated with a series of holes, in a spiral arrangement, which moves at a speed of 900 revolutions per minute. The light which penetrates the disc is known as the "flying spot" and is reflected, through a mirror, on to the face of the subject being televised. The holes in the disc being arranged in spirals, each spot of light is reflected to "hit" a different but consecutive cross section of the subject. Thus, through the use of scanning, every image is broken into these smaller elements which can be transmitted over the air. It is necessary, however, to translate these picture elements into some form which can be amplified and sent across great distances. Placed before the subject is a bank of platter-like reflectors which house the photo-cells, caesium cells sensitive to light which are capable of translating light into electrical impulses. These photo-electric cells radiate impulses which are the electrical equivalents of various graduations of light and which vary in intensity to the shade of light. Thus, with a dark color the corresponding impulse or signal is a weak one, darkness being an absence of light. Conversely, the lighter the color, the more intense the signal. The photo-electric ce!l acts in the same capacity as the microphone in sound broadcasting. In radio transmission the microphone translates each sound into a corresponding electrical impulse which is amplified and sent over the air. Sound as sound has only a limited carrying distance and could not as such be transmitted. Similarly, the light radiated from any one subject is not intense enough to carry through space without being eclipsed by the welter of other light sources. Following its translation into elec Fig. 2. Flying Spot Mechanism